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Seltec Compressor Seized?

75gmck25 on Sat July 03, 2010 2:02 PM User is offline

Year: 1975
Make: GMC
Model: K25
Engine Size: 350
Refrigerant Type: R134
Ambient Temp: 85
Country of Origin: United States

My truck originally used a GM A6 compressor, standard condenser, and R12. I converted the truck about 3 years ago using a Seltec 16 compressor and the # 12-0568A parallel flow condenser, along with new barrier hoses and a Ford blue orifice, high pressure switch, and 3 lbs of R134 (r12 charge had been 3 lbs, 12 oz).

- About two years after the conversion I had to recharge the system because it was leaking somewhere and had lost pressure. I tightened a couple of suspect fittings, had it recharged, and went on from there. However, the next time it only took about 6-8 weeks until I lost cooling again.
- I then replaced one bad O-ring (system was down to only 5 lbs) and added about 20 oz of R134 (i don't recall the pressures) and it started cooling again. I assumed this meant I was low on R134 again, and just needed to find the leak.
- I couldn't get back to it again for about 3 weeks, and by then it was back to no cooling. As soon as I put the small can of UV dye on the port it immediately kicked in the compressor. I added about another 8 oz of 134 I had left over, just so the compressor would keep running and circulate the dye. That was earlier this week. At that point there was no noise from the compressor and I had limited cooling. I let the A/C run for about 5-10 minutes before I shut it down.
- When I went back today to use a light and look for leaks, the belt started smoking because it could not turn the compressor.

The static pressure is running about 120 on both high and low, and I can't turn it on to check running pressures. The UV dye was from the parts store and it came in a small can that was supposed to give a 1-2 oz shot. The Seltec compressor uses PAG oil (150?), and this dye was supposed to be compatible with any type of oil.

I tried turning the clutch manually with a large screwdriver braced between the three nubs on the front, but it did not move. I was not sure that it should move freely when there was no power, so I did not want to force it.

What could be making the compressor and/or the clutch lock up? Have I screwed up the compressor somehow?



bohica2xo on Sat July 03, 2010 3:13 PM User is offline

So about 80 ounces of refrigerant has leaked from this system over 3 years. Along with that refrigerant went some (perhaps most) of your lubricating oil.

With a system already low on oil form repeated leaks, adding a few ounces of refrigerant to spin the compressor left it without enough refrigerant to return what might have been left of the oil in the system.

I suspect when you pull the OT, it will be dry as a bone in the desert sun. If the clutch hub will not turn with your fingers, it is dead. A smoking belt? um yeah it is locked up solid.

How much oil was initially charged into this hybrid system?


"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

75gmck25 on Sat July 03, 2010 3:28 PM User is offline

The compressor came originally from Arizona Mobile Air with the correct oil (I think it was PAG 150), and I followed their directions. I don't recall how much total was put in the system.

So you are saying the compressor is locked up completely and needs to be replaced, or is there something else I could do to break it loose?


TRB on Sat July 03, 2010 4:33 PM User is offlineView users profile

If you can't turn the hub of the compressor good chance the compressor is no longer good. I've never seen a Seltec lock up and then become free again. I tend to agree with bohica2xo lots of refrigerant losses along with oil will lead to a compressor failure. Seltec make a very good compressor but they won;t last without oil to lubricate the internals.


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